FRIDAY, Dec. 6 (HealthDay News) -- Genetics seem to play an important role in whether people respond to anti-smoking policies and may help explain why the number of smokers in the United States has remained stable in recent years instead of declining.

That's the finding of a new study by Yale School of Public Health researchers. They noted that smoking rates dropped sharply after the U.S. Surgeon General's landmark 1964 report about the dangers of smoking, but cessation rates have leveled off over the past 20 years despite increasingly strict measures -- such as higher taxes and no-smoking rules -- meant to persuade people to quit.

"We found that for people who are genetically predisposed to tobacco addiction, higher cigarette taxes were not enough to dissuade them from smoking," lead researcher Jason Fletcher, an associate professor in the department of health policy and management at the School of Public Health, said in a Yale news release.

He and his colleagues examined the association between state tobacco taxes and a nicotine receptor gene in adults. They found that variations in the nicotine receptor affected how people responded to higher tobacco taxes.

People with one genetic variant decreased their tobacco use by nearly 30 percent when faced with higher taxes, while those with another variant were not affected by higher taxes, according to the study published online Dec. 5 in the journal PLoS One.

"This study is an important first step in considering how to further reduce adult smoking rates," Fletcher said. "We need to understand why existing policies do not work for everyone so that we can develop more effective approaches."

The findings suggest that anti-tobacco strategies that do not rely on financial or social penalties may be needed to persuade many smokers to quit.

While the study found an association between certain gene variants and greater resistance to smoking cessation, it did not prove a cause-and-effect relationship.

Tobacco use is the leading preventable cause of death in the United States and causes more than 400,000 deaths a year, according to the U.S Centers for Disease Control and Prevention.